You needn’t take your shoes off when you enter someone’s house in Australia , _____ , of course , they’re very dirty .

1. A.
   before
2. B.
   since
3. C.
   when
4. D.
   unless

 You needn’t take your shoes off when you enter someone’s house in Australia , _____ , of course , they’re very dirty .

     A. before         B. since             C. when         D. unless

 You needn’t take your shoes off when you enter someone’s house in Australia , _____ , of course , they’re very dirty .

   A. if    B. except   C. when   D. unless

You needn’t take your shoes off when you enter someone’s house in Australia , _____ , of course , they’re very dirty .